Kyiv, Ukraine(CNN) Just two weeks ago, residents of the Ukrainian capital were tending to their shops, teaching schoolchildren or parked at their office desks.
The Russian invasion changed all that. Fighting literally for their lives, civilians, turned into volunteer soldiers, helped construct defenses with military precision -- and they are now manning them.
Trenches run deep into the woods that surround the highway leading in Kyiv from the south. Fortified fallback positions are ready for whatever comes next. Huge metal anti-tank barriers known here as "the hedgehogs" because of their spiky shape are placed at regular intervals along the road. And makeshift blockades made of sandbags and huge concrete blocks stand at every exit..
The people of Kyiv are determined to defend their city.
As Russian forces approach, the resolve of its residents is palpable -- with many appearing in good spirits.
Some flash a victory sign as vehicles pass by. The blue and yellow national flag can be seen everywhere.
At one checkpoint en route to Kyiv on Tuesday, volunteer defenders were handing out flowers to women in their cars to mark International Women's Day.
Many volunteers do not seem to be dressed warm enough for the freezing weather. They wear civilian clothes, with big coats and sweatpants an unofficial uniform. Their pants are mostly green, black or camouflage motif -- not the military kind -- but the civilian pattern made for hunting.
Some, but not all volunteers, are armed with automatic rifles and big knives.
Oleksiy Goncharenko, a volunteer manning one of the defense positions in Kyiv, told CNN that he works in four-hour shifts at the checkpoint.
His face is red from the cold. "It's OK. Just cold," he says, adding that "locals are giving us soups and things like that."
Almost 40,000 volunteers joined the Territorial Defense Forces in the first two days after the invasion began, according to the Ukrainian armed forces' chief of staff. In Kyiv alone, 18,000 picked up weapons when authorities called for volunteers and reservists to do so.
Those who couldn't join the forces (so many people signed up that the Territorial Defense Forces had to start turning people away) are helping in other ways.
They are making Molotov cocktails, sewing camouflage nets for barricades, distributing food, hot drinks and cigarettes to those standing guard. They are raising money for the military, building more road blocks and even painting over traffic signs in an attempt to confuse invading forces.
Kateryna Yurko, whose store was destroyed when a Russian missile hit nearby last week, is now spending her time driving back and forth between Kyiv and the Polish border, bringing humanitarian aid for infants and the elderly. She has also made Molotov cocktails for the troops, she says.
Oleksii Erinchak, who runs a bookstore and coffee shop in central Kyiv, has turned the space into a volunteer hub.
"We are trying to prepare ourselves for the worst-case scenario where we would be surrounded by Russian troops and all the supply networks would be destroyed. So we are trying to make sure that everyone and every building is prepared for this," he told CNN.
Another project the volunteers are working on is trying to encourage people to get to know their neighbors -- something that's not that common in a big city.
"If everything is blocked -- no internet connection, no phone calls -- you will be together with your neighbors (and) they can help you, you will not be alone," Erinchak said. Most of his work now focuses on establishing neighborhood networks for food and medicine distributions.
But Erinchak is still selling books, too, "...because there should be something normal happening, even in this situation," he said. The coffees, however, are free.
Closer to the city center, the defenses are stronger.
But here, it's the professionals manning the checkpoints. Tanks and weapon launchers are in position along the city's main arteries.
Kyiv's famed Maidan Square, which sits in the heart of the capital, is now a fortress. A big Ukrainian flag flies high above the site of the 2014 protests.
The capital's parks now serve as staging grounds for military vehicles; shopping areas lined with boutiques, hip cafes and fancy restaurants are now bordered with barriers made of sandbags and blocks of concrete.
And electronic signs that normally display traffic information and commercials are now calling for "NATO to close the skies" and proclaiming "Glory to Ukraine."
One of those signs addresses Russian troops directly. "Russian soldiers, stop. How can you look your children in the eye. Go home and be human," it reads.
Near Kyiv police headquarters, eight men -- two policemen and six National Guards -- man a checkpoint, stopping every vehicle that comes through.
National Guard reservist Oleksandr, who asked CNN to only use his first name for his safety, said that he spends six hours at the post, then takes six hours to rest.
Usually, that means four hours sleep and two hours for anything else that needs to be taken care of: a shower, a shave, change of clothes, or a quick message to his family. Six hours is a long time to stand in the snow, he says -- it's cold.
Around the corner, a small shop remains open, even as every other business around it have closed. Liudmyla, who runs the shop, supplies coffee and cigarettes to the soldiers protecting the road in front of her store.
There aren't many other customers these days, says Liudmyla, who asked CNN to only be referred by her first name for safety reasons.
Most people are staying at home and are not venturing into the city center. Instead, they remain huddled in basements and subway stations. Liudmyla says she is determined to stay open and has brought in her husband Dmytro for support. "I work. He is protecting me," she says.
She says that "there are no words, emotions or reactions that could describe how I feel."
"We don't know which day of week is today, but we know for sure it's the thirteenth day of war," she says, adding that she believes that Ukrainians will be "victorious."
Instead of a goodbye, Liudmyla ends our conversation with what many are thinking here: "Putin is a d***!"